In the field of medicine where treatment of a disease depends on inactivation or destruction of a certain tissue or biological target, the need of a highly focused treatment energy is important to spare the surrounding healthy tissues. The most accurate systems used for this purpose today rely on an ultimate fixation of a stereotactic system to the target body.
Stereotactic framebased radiosurgery uses sophisticated computerized imaging to provide data for an area of treatment in a patient body. Precisely targeting of narrow beams of radiation to such areas of treatment is based on a stereotactic frame attached to the patient. Thus it is for instance possible to effectively destroy small tumors or close down abnormal blood vessels. Stereotactic surgery, uses equivalent methods to define the target of invasive procedures. These techniques require targeting accuracies down to one millimeter or less. For instance in stereotactic radiosurgery or radiotherapy of the brain, very precise delivery of radiation to such a small volume of the brain, e.g. where a tumor is located, is provided, while sparing of the surrounding normal brain. This minimizes the effect of the radiation on the normal brain and reduces the risk of side effects.
For instance, U.S. Pat. No. 5,681,326 or U.S. Pat. No. 5,634,929 disclose stereotactic frame systems that benefits from a tight fixation of a mechanical frame to an anatomically fixed bone structure of the patient, which defines a stereotactic coordinate system. With the frame as reference, any point in three dimensions can be defined with high precision. Known systems use such a mechanical frame both during preoperative imaging and during surgery subsequent a planning thereof based on the imaging. However, the frame thus remains attached to the patient over a long period of time, which is inconvenient for the patient.
However, registering the physical space with the image space is difficult, in particular if high precision is required for the treatment of small areas in the imaged patient body, e.g. in the millimeter range.
Furthermore, when the imaging modality used to obtain the patient data for presurgical planning is a magnetic resonance imager (MRI) in conjunction with a frame based stereotactic system, one or more of the following issues may be taken into consideration. The physical size of the mechanical frame may not allow the operator to choose a receiver coil of the MRI freely. Modern scanners use receiver coils that are tightly fit to the surface of the patient in order to optimize the imaging procedure. Therefore, a patient having a stereotactic frame affixed, may not fit into a MRI.
Furthermore, the material of the mechanical frame may affect the performance of an imager, such as a MRI. Hence certain image procedures may be prohibited, for example diffusion weighted magnetic resonance imaging.
Moreover, in case the material of the mechanical frame is conducting, the frame might increase the geometrical distortions and/or increase the risk of local heating of the patient in the areas where the mechanical frame is fixated.
Also, for certain treatment modalities such as radiation based, the optimal treatment goal is often best met by repeated treatment sessions over a certain time period of days or weeks. To gain an ultimate stereotactic treatment accuracy with repeated treatment the frame has to remain fixed to the patient body during the whole treatment period or alternatively be removed after each treatment session and relocated/fixed again before the next treatment session, which is cumbersome both for the patient and the health care system.
The patient positioning in frame based stereotactic therapy relies on a mounted mechanical frame. The frame has to remain attached to the patient during imaging and therapy. Thus, when fractioning the treatment into a plurality of treatment fractions, the frame needs to be mounted to the patient for a long time. Alternatively, a new set of images and target planning has to be performed before each treatment fraction. This makes such a procedure expensive, time consuming, and little patient friendly.
Thus, there is a need for an improved stereotactic therapy system and/or method.
Hence, an improved stereotactic therapy system and/or method would be advantageous, and in particular a stereotactic therapy system allowing for increased flexibility, cost-effectiveness, accuracy, patient friendliness, and/or patient safety, would be advantageous.